1 files changed, 48 insertions, 54 deletions

diff --git a/kernel/mm/zpool.c b/kernel/mm/zpool.c
index bacdab6e4..fd3ff719c 100644
--- a/kernel/mm/zpool.c
+++ b/kernel/mm/zpool.c
@@ -18,11 +18,9 @@
 #include <linux/zpool.h>
 
 struct zpool {
-	char *type;
-
 	struct zpool_driver *driver;
 	void *pool;
-	struct zpool_ops *ops;
+	const struct zpool_ops *ops;
 
 	struct list_head list;
 };
@@ -73,34 +71,8 @@ int zpool_unregister_driver(struct zpool_driver *driver)
 }
 EXPORT_SYMBOL(zpool_unregister_driver);
 
-/**
- * zpool_evict() - evict callback from a zpool implementation.
- * @pool:	pool to evict from.
- * @handle:	handle to evict.
- *
- * This can be used by zpool implementations to call the
- * user's evict zpool_ops struct evict callback.
- */
-int zpool_evict(void *pool, unsigned long handle)
-{
-	struct zpool *zpool;
-
-	spin_lock(&pools_lock);
-	list_for_each_entry(zpool, &pools_head, list) {
-		if (zpool->pool == pool) {
-			spin_unlock(&pools_lock);
-			if (!zpool->ops || !zpool->ops->evict)
-				return -EINVAL;
-			return zpool->ops->evict(zpool, handle);
-		}
-	}
-	spin_unlock(&pools_lock);
-
-	return -ENOENT;
-}
-EXPORT_SYMBOL(zpool_evict);
-
-static struct zpool_driver *zpool_get_driver(char *type)
+/* this assumes @type is null-terminated. */
+static struct zpool_driver *zpool_get_driver(const char *type)
 {
 	struct zpool_driver *driver;
 
@@ -127,6 +99,41 @@ static void zpool_put_driver(struct zpool_driver *driver)
 }
 
 /**
+ * zpool_has_pool() - Check if the pool driver is available
+ * @type	The type of the zpool to check (e.g. zbud, zsmalloc)
+ *
+ * This checks if the @type pool driver is available.  This will try to load
+ * the requested module, if needed, but there is no guarantee the module will
+ * still be loaded and available immediately after calling.  If this returns
+ * true, the caller should assume the pool is available, but must be prepared
+ * to handle the @zpool_create_pool() returning failure.  However if this
+ * returns false, the caller should assume the requested pool type is not
+ * available; either the requested pool type module does not exist, or could
+ * not be loaded, and calling @zpool_create_pool() with the pool type will
+ * fail.
+ *
+ * The @type string must be null-terminated.
+ *
+ * Returns: true if @type pool is available, false if not
+ */
+bool zpool_has_pool(char *type)
+{
+	struct zpool_driver *driver = zpool_get_driver(type);
+
+	if (!driver) {
+		request_module("zpool-%s", type);
+		driver = zpool_get_driver(type);
+	}
+
+	if (!driver)
+		return false;
+
+	zpool_put_driver(driver);
+	return true;
+}
+EXPORT_SYMBOL(zpool_has_pool);
+
+/**
  * zpool_create_pool() - Create a new zpool
  * @type	The type of the zpool to create (e.g. zbud, zsmalloc)
  * @name	The name of the zpool (e.g. zram0, zswap)
@@ -139,15 +146,17 @@ static void zpool_put_driver(struct zpool_driver *driver)
  *
  * Implementations must guarantee this to be thread-safe.
  *
+ * The @type and @name strings must be null-terminated.
+ *
  * Returns: New zpool on success, NULL on failure.
  */
-struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
-		struct zpool_ops *ops)
+struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
+		const struct zpool_ops *ops)
 {
 	struct zpool_driver *driver;
 	struct zpool *zpool;
 
-	pr_info("creating pool type %s\n", type);
+	pr_debug("creating pool type %s\n", type);
 
 	driver = zpool_get_driver(type);
 
@@ -168,9 +177,8 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
 		return NULL;
 	}
 
-	zpool->type = driver->type;
 	zpool->driver = driver;
-	zpool->pool = driver->create(name, gfp, ops);
+	zpool->pool = driver->create(name, gfp, ops, zpool);
 	zpool->ops = ops;
 
 	if (!zpool->pool) {
@@ -180,7 +188,7 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
 		return NULL;
 	}
 
-	pr_info("created %s pool\n", type);
+	pr_debug("created pool type %s\n", type);
 
 	spin_lock(&pools_lock);
 	list_add(&zpool->list, &pools_head);
@@ -202,7 +210,7 @@ struct zpool *zpool_create_pool(char *type, char *name, gfp_t gfp,
  */
 void zpool_destroy_pool(struct zpool *zpool)
 {
-	pr_info("destroying pool type %s\n", zpool->type);
+	pr_debug("destroying pool type %s\n", zpool->driver->type);
 
 	spin_lock(&pools_lock);
 	list_del(&zpool->list);
@@ -222,9 +230,9 @@ void zpool_destroy_pool(struct zpool *zpool)
  *
  * Returns: The type of zpool.
  */
-char *zpool_get_type(struct zpool *zpool)
+const char *zpool_get_type(struct zpool *zpool)
 {
-	return zpool->type;
+	return zpool->driver->type;
 }
 
 /**
@@ -347,20 +355,6 @@ u64 zpool_get_total_size(struct zpool *zpool)
 	return zpool->driver->total_size(zpool->pool);
 }
 
-static int __init init_zpool(void)
-{
-	pr_info("loaded\n");
-	return 0;
-}
-
-static void __exit exit_zpool(void)
-{
-	pr_info("unloaded\n");
-}
-
-module_init(init_zpool);
-module_exit(exit_zpool);
-
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
 MODULE_DESCRIPTION("Common API for compressed memory storage");